Abstract
The resistance across a step on ultrathin films of three different topological insulators, , , and , was measured through anisotropy in two-dimensional resistivity by using the in situ square four-point probe method in ultrahigh vacuum. The step resistance was much larger for than for in the range of 1–10 quintuple-layer thickness, due to the smaller critical thickness for isolation of topological surface states in . The transmission probability of carriers across a step is much higher for the bulk-insulating than bulk-metallic , due to prevention of scattering of surface-state carriers into the bulk states. We were able to deduce microscopic information concerning the transmission probability at individual steps from the resistance data obtained macroscopically.
- Received 29 April 2020
- Revised 31 July 2020
- Accepted 12 August 2020
DOI:https://doi.org/10.1103/PhysRevB.102.115418
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